What is the tab at the bottom of the HS-WD100+ for?

[CinBRandon]

What is the tab for, that is located at the bottom of the HS-WD100 and HS-WD200 dimmers?

[randy]

What is the tab for, that is located at the bottom of the HS-WD100 and HS-WD200 dimmers?

It is called an air gap. It is a disconnect required on the dimmers. When you pull it out it disconnects the line from the dimmer. It is for safety when changing light bulbs. A dimmer uses a solid state device and could possibly leak enough current to hurt you when changing a bulb. The HS-WS models do not have it because they are relays and have a natural air gap when off.